(_ UnitedStates.

Departm Agricultureentof Prevention, Detection, and

" Forest Service _ _ Control of Nursery Tree Diseases

North Central

ForestExperiment

Station Thomas H. Nicholls

ResearchNoteNC-348

ABSTRACT.---Describes integratedcontrolmeas- Cultural Control

uresinvolvingchemical,cultural,genetic,biological,

and legalcontrolmethodsthatcan be used to Culturalcontrolmeasuresare directedat avoidinga

reducethe impactoftree diseasesinnurseries, diseaseorsuppressingthecausalagent,andthey

can oftenbeworkedintonormalculturalpractices.

KEY WORDS" Diseasecontrol,nurserymanage- Mostculturalpracticesinvolvealteringtheenvironment,pestguidelines, ment,theconditionofthe host,orthe behaviorof

the diseasebyreducingthe amountoftheinoculum

or byavoidingthe diseaseby choiceof location,

Nurserytree diseasesandotherpestscan cause timeof planting,plantspacing,nutrition,etc.

heavyeconomiclossesinthe nurserybydeforming

orkillingtrees,slowingtheirgrowth,discoloring

foliage,,increasingsusceptibilityto otherorganisms Genetic Control

orenvironmentalstresses,and delayingrotations.

' To preventor reducesuchlosses,a well-conceived Geneticcontrolsinvolvethe use of immune,tolerdiseasecontrolprogramshouldbe established, ant,or resistantspeciesorvarietiesto preventor

basedon adequateknowledgeof the pathogen,the reducediseaseimpact. Thismethodutilizes

host,:andtheclimaticandculturalconditionsunder techniquesthatcontributeto alteringthe physiologiwhichtreesare grownorstored. Effectivecontrol cal processes,structuralnature,or habitsof individof mostdiseasesrequiresoneor morechemical, ual plantsor plantpopulationsinorderto make

cultural,genetic,biological,and legalcontrol _ themtolerateor resistinfection.

methods. Thispaperwillfocus on someof the

moreimportantdiseaseprevention,detection,and

controlproceduresthatcan be used to helpproduceand protecthealthynurserytreestock. It will

alsopresentsomegeneralguidelinesfor preventing

or reducingnurserypests.

" Chemical Control

Chemicalcontrolisone ofthe mosteffectiveways

to combatdiseases(fig.l). It involvespreventing

inoculum(anypartof a pathogen,suchasa sPore,

whichisableto infecta host)fromenteringthe host

and infectingit. To accomplishthis,fungicides

have been usedto preventgrowthorsporulationof

pathogens,orto killor inactivatetheinoculumat its

source,intransit,orat thesite ofinfection.

Figure1.--Applyingfungicidesisoneof themost

effectivewaystocombatfungusdiseases. Unprotectedredpinetreesin thebackgroundwereinfected

Thomas H. Nicholls isa WildlifeBiologist(formerly witha fungusdiseasecalled LophodermiumseditioPrincipalPlantPathologist)withthe NorthCentral sum;youngtreesin theforegroundwereprotected

ForestExperimentStation,St. Paul,Minnesota. fromthisdiseaseby maneb.
Biological Control whichcan theninfectnurseryseedlings.

" 9. Nurserypestinspectorsshouldvisitnurseries

Biologicalcontrolis_thedeliberateuseof a whensymptomsorsignsare mostapparent.

pathogen'snaturalenemies,suchas predators, Sometimesnurseriesarecertifiedpest-freebeparasites,and otherdiseases,to regulatepest causetheywere examinedat the wrongtime.

populations.Once naturalenemiesbecome 10. Do notshipinfectednurserystock.

permanentresidents,pestsare lesslikelyto 11. Do notplantdiseasedtreesor treesthatare

increaseto damagingproportions.The lasting suspectedto be diseased. If diseasedtrees are

natureof biologicalcontrolmakes itrelativelyinex- planted,theycan infectothertrees inthe

pensiveas well as environmentallysafe. plantingandepidemicsmayresult.

12. Do notexchangestockbetweennurseries.

Legal Control Severalpestshavebeen introducedfromone

nurseryto anotherwheninfectedstockhas

Legalcontrols,suchas quarantines,are designed been exchanged.

to prevent.theintroductionof inoculumandthe 13. Do notexchangenurseryequipmentunlessit is

establishmentofa pathogenwithinan uninvaded properlycleanedand sterilized.

area. Once nurserydiseasepestsenter new,unin- 14. Use onlyregisteredpesticidesandfollowlabel

fectedareas,theycommonlyswelltoepidemic directions.

levelsand are moredifficultto control. 15. Maintaina well-balanceddiversityof species.

• Thiswilltemperpestoutbreaks.

Pest Guidelines 16. Lookatthe economicadvantagesof available

• alternativecontrols. Somecontrolsmay be

Here aresomegeneralguidelinesthatcan help moreeffectiveandlesscostlythan others.

preventor reducenurserypestproblems. 17. Keep accuraterecordsofcontrolsuccesses

andfailures. Thiswill helpyou notmakethe

' 1. Beforeseedingor plantingan area,checkto samemistaketwice!

Seewhatdiseasesor insectsare presentthat

may harmthetrees,andthen developan action Summary

planto deal quicklywiththosepests.

2. Train workersto be alertforand to recognize An integratedcontrolapproachusingthe informapests, tion presentedinthispapercan helppreventor

3. Monitornurseriesand storagefacilitiesoften,for reducetheimpactof majorpestsintree nurseries

earlydetectionand controlcan preventserious (fig.2). Itsultimatesuccessdependson adequate

losses. Regularlyobserveandrecordthecon- dollars,teamwork,earlydetection,positivepest

ditionofyourplants,the abundanceof both identification,andpropertiming,selection,and

pests andplantdamage,andyourmanagement applicationofavailablecontrols.

activitiesandtheireffects.

+ 4. Seek professionalhelpif youare unsureofWhat

+ pestyou are dealingwithorwhatto do aboutit.

• , Withthishelp, determineand useavailable

controls for problemsseriousenoughto cause

economiclosses.

5. +Identifthe Y pestsothatyoucan choosethe

most.effectivecontrols.

6. Applycontrolsat propertimesandonlywhen

necessary. Thissavesmoneyand labor,andit

preventsthe needlessintroductionofchemicals

intotheenvironment. •

7. Maintain,store,transport,andplanttrees under

properconditions.Improperhandlingof trees

can predisposetreesto pestscausingserious Figure2.--Knowing,selecting,andapplyingeffective

losses, pestcontrolsat thepropertimewillhelpproduceand

8. use non-hostwindbreaks. Windbreaksof protecthealthytrees.

Susceptiblespeciesthatare grownnear nursery

beds.sometimesserveasreservoirsfor pests, Motto" Discovering and disseminating knowl-

. edge about natural resources. 2